1. Field of the Invention
This invention relates to the field of pressure initiated electrical systems and more particularly to a device for preventing unintended ejection and jettisoning of aircraft ejection seats and canopies in systems using an electro ballistic escape sequence.
2. Description of Related Art
Ejection seat systems are an essential part of many military airplanes and a few civilian airplanes. Such seats are well-known as a way of permitting the occupants of the aircraft to safely escape the airplane in the face of an emergency, so that a parachute can be safely employed to lower the occupant to the ground.
In such systems, the two primary concerns are the speed at which the occupant can be ejected after initiating the ejection sequence, and occupant safety. When ejection is required, the pilot and passengers must be able to clear the aircraft as quickly as possible, while at the same time avoid hitting any part of the aircraft, or each other. It is also essential to provide means for preventing unintended ejection of the seat. Unintended ejection could leave a plane without control and endanger the ejected pilot and passengers.
One system which has been proposed, the Electro Ballistic Escape Sequencing System (EBESS), uses gas pressure to initiate thermal battery ignition of electro explosive devices (EED's) which activate the various subsystems which make up the escape sequence. The system includes both redundancy and a time delay backup, and has proven to be relatively fast and reliable in comparison with previous systems.
Nevertheless, despite its numerous advantages, the currently proposed EBESS suffers from the critical drawback that it has not heretofore been possible to entirely prevent unintended ejection and jettisoning of the canopy and seats. Unintended ejections can be caused by a variety of forces, including nature (e.g., lightning); battle damage (e.g., a projectile through the thermal battery); maintenance errors; and a variety of man-made energy sources, including radio frequency emissions, electromagnetic pulses, and lasers.